WASHINGTON — The US Senate on Wednesday tabled an amendment to cut off military aid to Egypt, but debate on the chamber floor offered a preview of the 2016 Republican presidential primary.

Within an hour-long debate about F-16s, M1 tanks and whether the Egyptian military orchestrated a coup, potential GOP presidential candidates Sens. Rand Paul of Kentucky and Marco Rubio of Florida underscored their differing foreign policy and national security approaches.

One wants Washington to stop sending billions in aid dollars to other nations. The other wants to keep that spigot flowing, but with major changes. Both are favorites of likely GOP voters. And both of their envisioned approaches likely would hurt US arms manufacturers.

Sen. John McCain of Arizona, the GOP’s 2008 presidential nominee, told reporters the differences espoused Wednesday by Paul and Rubio will be a key issue as Republicans select their 2016 nominee.

“You’re seeing a debate within the Republican Party about the role of America in the world. And that could spill over into the presidential campaign,” McCain said. “No matter who is nominated, that debate is going to go on in the Republican Party.”

Paul, the libertarian tea party favorite, made clear he believes Washington should send fewer dollars abroad. Those billions could better be spent on things such as repairing crumbling infrastructure at home.

He criticized President Barack Obama for — as many of his recent predecessors have — sending F-16 fighter jets and M1 tanks to Egypt’s military while “Detroit decays” and Chicago descends “into a war zone.”

“When you see boarded up houses in Detroit,” Paul said on the Senate floor, “think about your politicians who chose to send that money to Egypt.”

Paul’s amendment, offered to a Senate transportation appropriations bill, would have eliminated “military foreign assistance to Egypt based upon current law, which the United States is legally prohibited from providing foreign assistance to nations that experience a military coup d’état.”

Instead, it would require that any aid meant for Egypt be used instead to address bridges in the US that have fallen into disrepair.

“Foreign aid doesn’t go to foreign people,” Paul said. “It goes to foreign despots” to buy things like “private jets.” He even suggested the Egyptian military might one day use its F-16s and M1s against the United States.

Paul’s comments about his amendment suggest, as diplomat and commander in chief, he would dramatically shrink the amount of funds and weapons Washington annually sends around the globe. That would be a big blow to US defense contractors that already feel squeezed by declining American military budgets.

Rubio, meanwhile, later issued a vision of his foreign policy and national security approach more in line with the so-called GOP establishment.

He called for Washington to keep sending about $1.5 billion annually to Egypt — but with changes.

“They probably don’t need any [more] F-16s,” Rubio said.

The Florida Republican called for a complete recalibration of US foreign aid, including the money it annually sends to Cairo.

Rubio, as president, according to his comments Wednesday and in the past, would still send dollars overseas. But he believes those funds should promote things such as economic and governmental development in nations like Egypt — without necessarily building other nations’ militaries with American-made weapon systems. This also would be a big blow to US weapons manufacturers.

Paul and Rubio are both favorites of likely Republican voters, and analysts say each is well positioned for the coming presidential nomination race.

Rubio’s favorability rating among Republicans is 58 percent, and Paul’s is 56 percent, according to a recent Gallup poll. They both, however, trail the 2012 GOP vice presidential nominee, House Budget Committee Chairman Rep. Paul Ryan of Wisconsin. Sixty-nine percent of likely GOP voters polled by Gallup have a favorable opinion of Ryan.